This invention is addressed to use of irrigation and watering systems in the farming industry, as well as sprinkling systems in smaller applications such as residential watering systems and to other applications which may require mixing in a short reach of conduit of an injectate in an effluent flow. Particularly, in the irrigation of large fields in farming, water obtained from a well or surface water source is distributed to the fields through medium pressure pipes with branch lines which feed lateral sprinkler lines equipped with sprinkler heads. It is often desirable to make applications of fertilizers or pesticides concurrently with the irrigation process, and such application is typically effectuated by injection of the additive in liquid form into irrigation water at some point along the length of the conduit pipe leading to the branch lines of the system. Injection has been accomplished by any number of means ranging from mere injection of the liquid additive through an aperture in the conduit pipe, allowing the additive to blend with the irrigation water as it may, to injection systems which are an integral part of the conduit pipe and which disperse the additive into the main flow at a calculated rate. These integral systems, as disclosed in the prior art, accomplish integration of the additive into the system, but do so without attention to relative uniform concentrations of additive being dispersed. In other words, the currently used systems do not achieve mixture of equal concentrations of water and additive within the main conduit, and do not achieve equal concentrations prior to any branching of the main conduit into the lateral irrigation lines. The mixing of two nonmiscible fluids is dependent upon the turbulence of water in the conduit pipe and the pipe length prior to bifurcation or branching to lateral lines. A pipe length roughly 20 times the diameter of the pipe is needed to produce adequate mixing of the liquids. Frequently, geometrical constraints and varying irrigation systems do not provide the length of pipe necessary to accommodate thorough mixing of the liquids. The failure of proper mixing and distribution results in over-application of additive in some areas of the field while other areas suffer from an application of too little additive. The present invention has been designed to accomplish injection and thorough mixing of liquid additives into irrigation systems in the shortest possible distance. Calculation of optimum dispersal distances and utilization of monitored flow rates of additive into the flow of water assures maximum mixture and optimal application of the additive. The advantageous use of the present invention over prior art inventions is more fully appreciable below.